.\"
.\" SPDX-License-Identifier: BSD-2-Clause
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.\" Copyright (c) 2008 Alexander Motin <mav@FreeBSD.org>
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.Dd October 3, 2025
.Dt SDHCI 4
.Os
.Sh NAME
.Nm sdhci
.Nd PCI SD Host Controller bridge driver
.Sh SYNOPSIS
To compile this driver into the kernel, place the following lines in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device mmc"
.Cd "device mmcsd"
.Cd "device sdhci"
.Ed
.Pp
Alternatively, to load the driver as a module at boot time, place the
following lines in
.Xr loader.conf 5 :
.Bd -literal -offset indent
mmc_load="YES"
mmcsd_load="YES"
sdhci_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
driver supports PCI devices with class 8 and subclass 5 according to
SD Host Controller Specification.
Driver supports up to six high speed 4bit MMC/SD slots per controller.
Driver attaches mmc bus to the respective slot on card insertion and
detaches it on card removing.
.Sh HARDWARE
The
.Nm
driver supports the SD Host Controller Specification.
When attaching via the PCI bus,
the controller is automatically configured.
Many SoC chips provide a SDHCI controller directly mapped to I/O memory.
For those, the controller may be configured using
.Xr fdt 4
or
.Xr acpi 4
methods, supplied by your board's vendor.
.Pp
Unlike most other drivers that support a generic standard,
.Nm
requires a large number of quirks to cope with hardware bugs,
proprietary registers and poorly specified power management.
While many chipsets from
Intel, Xilinx, Rockchip, Frescale, Ricoh, and TI have these entries,
suboptimal performance may result when using some controllers.
Quirks and custom configuration are most often required
when the device is configured via
.Xr fdt 4
or
.Xr acpi 4 .
.Sh SEE ALSO
.Xr mmc 4 ,
.Xr mmcsd 4
.Rs
.%T "SD Specifications, Part 2, SD Host Controller, Simplified Specification"
.Re
.Sh AUTHORS
.An Alexander Motin Aq Mt mav@FreeBSD.org
